FIG. 5(e) shows a thin film head of the floating type, which comprises a head slider 10 formed with chamfers 12, ABS (air bearing surface) faces 13, etc. on the surface thereof to be opposed to the signal face of recording media. The head slider 10 has a pair of head elements 20, 20 formed by the thin film deposition process and photolithographic techniques on a face thereof orthogonal to the above-mentioned surface,
The illustrated floating-type thin film head is an inductive thin film head wherein the head element 20 comprises a pair of magnetic films arranged with a gap portion formed therebetween. Magnetoresistive thin film heads comprising a magnetoresistive element also include floating-type thin film heads which comprise a similar head slider and which are fabricated by the thin film deposition process and photolithographic techniques.
FIG. 5(a) to FIG. 5(e) show a process for producing floating-type thin film heads.
With reference to FIG. 5(a), a multiplicity of head elements 20 are formed by the thin film deposition process and photolithographic techniques on a substrate of Al.sub.2 O.sub.3 -TiC or like ceramic, and a protective layer (not shown) of SiO.sub.2, Al.sub.2 O.sub.3 or the like is formed to a thickness of about 50 .mu.m over the substrate to cover the head elements 20. The ceramic substrate 11 is then divided by array separating grooves 14 into arrays each having a plurality of head elements 20 as seen in FIG. 5(b). These arrays are to be divided into head chips each having one pair of head elements 20, 20 by chip separating grooves 15 which will be formed in a later step as indicated in the broken lines.
Next as shown in FIGS. 5(c) and (d), grooves 16 are formed in the surface of the ceramic substrate 11 of each array which surface is to be opposed to recording media, followed by formation of a chamfer 12 and ABS faces. The substrate is thereafter eventually divided by the above-mentioned chip separating grooves into head chips of specified shape as shown in FIG. 5(e).
With an increase in the recording density in recent years, the track width has become greatly diminished, giving rise to a need to give the head element a depth with the highest possible accuracy, so that the medium-opposed surface is finished with high precision in depth defining working.
The process for producing conventional thin film heads of the floating type is such that as shown in FIG. 5(a) to FIG. 5(e), a protective layer covering many head elements 20 is formed over the substrate 11, which is thereafter divided into chips by machining. The machining work therefore produces a sharp edge E of 90 deg at each of opposite sides of the protective layer 30 of the resulting head chip as shown in FIG. 2.
When the floating-type thin film head is mounted in a magnetic disc device and used for recording or reproducing signals, a lateral air current due to the rotation of the disc will act on the side face of the head slider 10 as indicated by arrows in FIG. 2 especially in the case where the thin film head is positioned at an increased skew angle due to a reduction in the size of the head. This entails the problem that the thin film head, which is subjected to the force of the lateral air current, is unable to retain its position with stability.
Further with the process for producing conventional floating-type thin film heads, the step of forming the protective layer of SiO.sub.2, Al.sub.2 O.sub.3 or the like on the surface of the substrate 11 by sputtering involves the problem that internal stress warps the substrate 11. If the warped substrate 11 is divided into head chips, the chips vary in the precision of the depth defining work, failing to afford heads which exhibit the desired performance.